chemistry help?

Method 1:

Molar mass of Al = 27.0 g/mol
Molar mass of Al₂O₃ = (27.0×2 + 16.0×3) g/mol = 102.0 g/mol

2Al₂O₃ → 4Al + 3O₂
Mole ratio Al₂O₃ : Al = 2 : 4

Moles of Al₂O₃ decomposed = (6.05 kg) / (102.0 g/mol) = 0.0593 kmol
Moles of Al produced = (0.0593 kmol) × (4/2) = 0.1186 kmol
Mass of Al produced = (0.0086 kmol) × (27.0 g/mol) = 3.20 kg

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Method 2:

(6.05 kg Al₂O₃) × (1 mol Al₂O₃ / 102.0 g Al₂O₃) × (4 mol Al / 2 mol Al₂O₃) × (27.0 g Al / 1 mol Al)
= 3.20 kg Al

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Method 3:

Mass of 1 mol Al₂O₃ = (27.0×2 + 16.0×3) g = 102.0 g
Mass of Al in 1 mol Al₂O₃ = 27.0×2 = 54.0 g

Mass of Al produced = (6.05 kg) × (54.0/102.0) = 3.20 kg

Roger the mole provided both the answer and the work needed to get the answer.

But I have one slight problem with this question.  How is it that aluminum oxide, Al2O3, is to be decomposed? This question could have been a good way to teach some more chemistry. It's not like you can heat it up and it turns into aluminum and oxygen. Aluminum oxide is a very stable substance. In its natural form it is the chemical of rubies and sapphires (corundum).  Rubies and sapphires just don't decompose.
.... Al2O3(s) --> 2Al(s) + 3O2(g) ........ This is trickier than it looks

There is a way, and its similar to the decomposition of another very stable oxide (water).  The decomposition of alumina (Al2O3) is done by electrolyzing a mixture of molten aluminum oxide dissolved in molten cryolite (Na3AlF6).  The cryolite lowers the melting point of the mixture and provides an electrolyte which allows the mixture to conduct electricity so that Al2O3 can decompose. (The aluminum oxide is first recovered from its ore, called bauxite.)

3.20 kg Aluminum

(6.05 kg Al2O3) / (101.96128 g Al2O3/mol) x (2 mol Al / 1 mol Al2O3) x
(26.98154 g Al/mol) = 3.20 kg Al

Oxygen is a light-weight gas while Aluminum is a metal. In aluminum tri-oxide there are 2 molecules of aluminum and 3 of oxygen. The decomposition would yield approximately 6 kg of aluminum.